My husband did the rental thing with his mountain bike and was very happy going that route. It really gives you a feel for the bike and I think if you buy a bike they give you 1/2 your rental back. You may also want to check out the Felts as well, a lot of bang for the buck. Jack and Adam's carry them.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan